﻿// Copyright 2006 - Ricardo Stuven (rstuven@gmail.com)
//
// This file is part of MsSqlSpatial.
// MsSqlSpatial is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
// 
// MsSqlSpatial is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Lesser General Public License for more details.

// You should have received a copy of the GNU Lesser General Public License
// along with MsSqlSpatial; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 

using System;
using System.Data.SqlTypes;
using System.IO;
using GeoAPI.Geometries;
using Microsoft.SqlServer.Server;
using MsSqlSpatial;
using Aggregate = MsSqlSpatial.Aggregate<GeoAPI.Geometries.IGeometry>;

[Serializable]
[SqlUserDefinedAggregate(Format.UserDefined
    , IsInvariantToNulls = true
    , IsInvariantToDuplicates = true
    , IsInvariantToOrder = true
    , IsNullIfEmpty = false
    , MaxByteSize = 8000
    )]
public struct IntersectionAggregate : IBinarySerialize
{
    [NonSerialized] private IGeometry aggregate;
    [NonSerialized] private string cacheKey;

    #region IBinarySerialize Members

    public void Read(BinaryReader r)
    {
        Aggregate.Read(r, out cacheKey, out aggregate);
    }

    public void Write(BinaryWriter w)
    {
        Aggregate.Write(w, cacheKey, aggregate);
    }

    #endregion

    public void Init()
    {
        Aggregate.Initialize(out cacheKey, out aggregate);
    }

    public void Accumulate(SqlBytes ewkb)
    {
        IGeometry geometry = ConvertGeometry.ToGeometry(ewkb);
        if (geometry != null && !geometry.IsEmpty)
        {
            if (aggregate != null && !aggregate.IsEmpty)
            {
                aggregate = geometry.Intersection(aggregate);
                aggregate.SRID = geometry.SRID;
            }
            else
            {
                aggregate = geometry;
            }
        }
    }

    public void Merge(IntersectionAggregate Group)
    {
        if (Group.aggregate != null && !Group.aggregate.IsEmpty)
        {
            aggregate = aggregate.Intersection(Group.aggregate);
            aggregate.SRID = Group.aggregate.SRID;
        }
    }

    public SqlBytes Terminate()
    {
        return ConvertGeometry.ToSqlBytes(Aggregate.Terminate(cacheKey));
    }
}